Hello students, in this blog you can find important summary notes from the Chapter 7, Science , NCERT Book of Class 8. These notes can be used for preparation of various school Competitive Exams, Olympiads and also developing strong Fundamentals.
1. Deforestation : means clearing of forests and using that land for other purposes.
2. Trees in the forest are cut for :
– Procuring land for cultivation
– Building houses and factories
– Making furniture
– Using wood as fuel
3. Natural causes of deforestation are forest fires and severe droughts.
4. Consequences of deforestation :
– increases the temperature and pollution level on the earth
– increases the level of carbon dioxide in the atmosphere
– disturbs the balance in nature
– ground water level also gets lowered
– rainfall and the fertility of the soil will decrease
– there will be increased chances of natural calamities such as floods
– affects animal life
5. Plants need carbon dioxide for photosynthesis.
6. Carbon dioxide traps the heat rays reflected by the earth, causing global warming.
7. The increase in temperature on the earth disturbs the water cycle and may reduce rainfall, this could cause droughts.
8. Deforestation is a major cause which leads to the change in soil properties.
9. Fewer trees result in more soil erosion and removal of the top layer of the soil exposing the lower, hard and rocky layers. This soil has less humus and is less fertile. Gradually the fertile land gets converted into deserts. It is called desertification.
10. Deforestation affects soil in following ways :
– a decrease in the water holding capacity of the soil – reduced movement of water from the soil surface into the ground,
– other properties like nutrient content, texture etc. of the soil, also change
11. Biosphere is that part of the earth in which living organisms exist or which supports life.
12. Biological diversity or biodiversity, refers to the variety of organisms existing on the earth, their interrelationships and their relationship with the environment.
13. Wildlife Sanctuary : These are areas where animals are protected from any disturbance to them and their habitat.
14. National Park : These are areas reserved for wild life where they can freely use the habitats and natural resources.
15. Biosphere Reserve : These are large areas of protected land for conservation of wild life, plant and animal resources and traditional life of the tribals living in the area.
16. The Pachmarhi Biosphere Reserve consists of one national park named Satpura and two wildlife sanctuaries named Bori and Pachmarhi.
17. Wildlife sanctuaries, national parks, biosphere reserves etc., are protected areas for conservation of plants and animals present in that area.
18. The plants and animals found in a particular area are termed flora and fauna respectively of that area.
19. Endemic species : Those species of plants and animals which are found exclusively in a particular area. They are not naturally
found anywhere else.
20. Species : It is a group of population which are capable of interbreeding, meaning that the members of a species can reproduce fertile offspring only with the members of their own species and not with members of other species.
21. People living in wildlife sanctuaries are allowed to do certain activities such as grazing by their livestock, collecting medicinal plants, firewood, etc.
22. Satpura National Park is the first Reserve Forest of India.
23. Project Tiger was launched by the government to protect the tigers in the country.